Reducing Noise

21-1599.fm Page 14 Thursday, August 5, 1999 10:59 AM

The Automatic Noise Limiting (ANL) circuit helps keep background noise to a minimum. However, strong sources of electrical noise (such as your vehicle’s ignition, another radio, or spark plugs) might be more than the circuit can compensate for.

If you operate the TRC-499 with a ve- hicle’s engine off, you should not have any problems with noise. If you use the CB with the engine on, you can determine the source of the noise by turning off the engine and operating the CB with the ignition set to ACC. If most or all of the noise goes away, the problem is in your ve- hicle’s ignition or electrical system.

Here are a few hints to help you re- duce or eliminate such noise:

•Replace old ignition wires with new, high-voltage, noise-sup- pression wires.

•Install noise suppressors on your spark plugs, or install new spark plugs that have built-in suppressors.

•Be sure that the ground connec- tion (black wire) is secure.

If problems persist, check your alter- nator/generator, regulator, and gaug- es. Noise from these sources can be reduced or eliminated using bypass capacitors at various output voltage points.

Your local Radio Shack store has a wide selection of noise-suppression accessories.